U.S. patent application number 14/969112 was filed with the patent office on 2017-04-13 for method for manufacturing negative plate of secondary battery.
The applicant listed for this patent is Metal Industries Research & Development Centre. Invention is credited to Sung-Mao CHIU, Chi-Wen CHU, Yin CHUANG, Chia-Hung HUANG, Chun-Chieh WANG, Chia-Min WEI.
Application Number | 20170104213 14/969112 |
Document ID | / |
Family ID | 58498923 |
Filed Date | 2017-04-13 |
United States Patent
Application |
20170104213 |
Kind Code |
A1 |
HUANG; Chia-Hung ; et
al. |
April 13, 2017 |
METHOD FOR MANUFACTURING NEGATIVE PLATE OF SECONDARY BATTERY
Abstract
The present invention provides a method for manufacturing a
negative plate of a secondary battery, which includes the following
steps: providing multiple sheets of functional graphene;
compressing the functional graphene to form a graphene target;
providing copper foil, and forming a microstructure on a surface of
the copper foil, so as to strengthen attachment between a graphene
layer and the copper foil; depositing the graphene target on the
microstructure of the surface of the copper foil, to form the
graphene layer; and repairing the graphene layer by using an
excimer laser. The foregoing manufacturing method can greatly
prolong a cycle life of the whole graphene cathode, and increase a
reversible capacitance of a battery.
Inventors: |
HUANG; Chia-Hung;
(Kaohsiung, TW) ; CHIU; Sung-Mao; (Kaohsiung,
TW) ; CHU; Chi-Wen; (Kaohsiung, TW) ; CHUANG;
Yin; (Kaohsiung, TW) ; WANG; Chun-Chieh;
(Kaohsiung, TW) ; WEI; Chia-Min; (Kaohsiung,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Metal Industries Research & Development Centre |
Kaohsiung |
|
TW |
|
|
Family ID: |
58498923 |
Appl. No.: |
14/969112 |
Filed: |
December 15, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M 4/1393 20130101;
H01M 4/0404 20130101; H01M 4/587 20130101; H01M 4/661 20130101;
C01B 2204/22 20130101; H01M 4/133 20130101; H01M 4/366 20130101;
H01M 10/0525 20130101; H01M 4/043 20130101; H01M 2004/027 20130101;
H01M 10/052 20130101; Y02E 60/10 20130101; C01B 32/194
20170801 |
International
Class: |
H01M 4/587 20060101
H01M004/587; H01M 4/36 20060101 H01M004/36; C01B 31/04 20060101
C01B031/04; H01M 4/1393 20060101 H01M004/1393; H01M 4/133 20060101
H01M004/133; H01M 4/04 20060101 H01M004/04; H01M 4/66 20060101
H01M004/66; H01M 10/0525 20060101 H01M010/0525 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 13, 2015 |
TW |
104133524 |
Claims
1. A method for manufacturing a negative plate of a secondary
battery, comprising the following steps: providing multiple sheets
of functional graphene; compressing the functional graphene to faun
a graphene target; providing copper foil, and forming a
microstructure on a surface of the copper foil, so as to strengthen
attachment between a graphene layer and the copper foil; depositing
the graphene target on the microstructure of the surface of the
copper foil, to form the graphene layer; and repairing the graphene
layer by using an excimer laser.
2. The method for manufacturing a negative plate of a secondary
battery according to claim 1, wherein in the step of forming a
microstructure on a surface of the copper foil, the microstructure
is formed on the surface of the copper foil by using a femtosecond
laser.
3. The method for manufacturing a negative plate of a secondary
battery according to claim 1, wherein the microstructure is a
trench structure or a ladder structure.
4. The method for manufacturing a negative plate of a secondary
battery according to claim 2, wherein the microstructure is a
trench structure or a ladder structure.
5. The method for manufacturing a negative plate of a secondary
battery according to claim 2, wherein after the microstructure is
formed on the surface of the copper foil by using the femtosecond
laser, a subtler microstructure is formed on the surface of the
microstructure by using a picosecond laser.
6. The method for manufacturing a negative plate of a secondary
battery according to claim 1, wherein a method for manufacturing
functional graphene comprises: adding graphite to potassium nitrate
(NaNO.sub.3) and sulfuric acid (H.sub.2SO.sub.4) oxidant, to form a
graphite solution, and stirring the graphite solution; adding
deionized water to the graphite solution, performing ultrasound
oscillation, abandoning supernatant fluid after the oscillated
graphite solution stands still and layers, and then adding
hydrochloric acid water solution for cleaning; abandoning
supernatant fluid after centrifugation of the graphite solution at
a rotation speed, and repeatedly cleaning and centrifuging the
solution by using the hydrochloric acid water solution, to obtain a
graphite oxide solution; adding hydrazine to the graphite oxide
solution; and drying the graphite oxide solution, to obtain
functional graphene.
7. The method for manufacturing a negative plate of a secondary
battery according to claim 2, wherein after the graphite is added
to the potassium nitrate and the sulfuric acid oxidant, to form a
graphite solution, the method further comprises: adding catalyst
manganese peroxide (KMnO.sub.4) to the graphite solution, and
stirring the solution.
8. The method for manufacturing a negative plate of a secondary
battery according to claim 2, wherein in the step of adding
graphite to potassium nitrate and sulfuric acid oxidant, to form a
graphite solution, and stirring the graphite solution, the graphite
is 2 grams, potassium nitrate is 0.2 to 0.75 grams, sulfuric acid
is 70 milliliters, and manganese peroxide is 3 grams, stirring
temperature is below 80.degree. C., and a stirring time is 2
hours.
9. The method for manufacturing a negative plate of a secondary
battery according to claim 2, wherein in the step of adding
deionized water to the graphite solution, performing ultrasound
oscillation, abandoning supernatant fluid after the oscillated
graphite solution stands still and layers, and then adding
hydrochloric acid water solution for cleaning, after the deionized
water is added to the graphite solution, the method further
comprises: adding hydrogen peroxide (H.sub.2O.sub.2), and then
using deionized water again for attenuation.
10. The method for manufacturing a negative plate of a secondary
battery according to claim 2, wherein in the step of adding
deionized water to the graphite solution, performing ultrasound
oscillation, abandoning supernatant fluid after the oscillated
graphite solution stands still and layers, and then adding
hydrochloric acid water solution for cleaning, a ratio of
hydrochloric acid to water in the hydrochloric acid water solution
is 1:10.
11. The method for manufacturing a negative plate of a secondary
battery according to claim 2, wherein in the step of adding
hydrazine to the graphite oxide solution, the graphite oxide
solution is 3000 CC; and the added 50 ml hydrazine is recirculated
for 24 hours at 100.degree. C.,
Description
BACKGROUND
[0001] Technical Field
[0002] The present invention relates to a method for manufacturing
a negative plate of a secondary battery, and in particular, to a
method for manufacturing a negative plate of a secondary battery,
where defects inside graphene are structurally recovered by using
an excimer laser, so that a cycle life of an entire graphene
cathode can be greatly prolonged and a reversible capacitance of
the battery can be increased.
[0003] Related Art
[0004] In the prior art, a solid electrolyte interface film (SEI
film) is formed on a surface of a negative plate, so that when
solvating lithium ions in an electrolyte enters the negative plate
through the SEI film, the lithium ions are separated from solvating
solvent molecules without bringing a delamination problem to the
negative plate. An existing SEI film is classified into two kinds:
a reactive SEI film and a reduction SEI film, However, these SEI
films are added into an electrolyte in the form of an additive. The
SEI film is formed through polymerization after an electrochemical
reaction, and is attached to the surface of the negative plate.
Therefore, a polymerization effect thereof and a capability of
separation from the solvent molecules are subject to an
electrochemical polymerization effect of the SEI film, In addition,
the forming the SEI film on the surface of the negative plate
easily brings a dissolution phenomenon to the electrolyte, which
affects electrical performance of a lithium battery. Moreover, the
SEI film is coated on the negative plate in an attraction manner,
and is easily separated from the negative plate under a
high-temperature operation. Therefore, an attraction capability of
the SEI film also affects its capability of separation from the
solvent molecules. In addition, gas is easily produced when the SEI
film is formed through polymerization, which also affects the whole
performance of the SEI film.
[0005] A conventional technology for manufacturing graphene
includes methods such as mechanical exfoliation, epitaxial growth,
chemical vapor deposition (CVD), and chemical exfoliation. Graphene
with high quality can be produced by using the mechanical
exfoliation and the epitaxial growth, but large-area graphene
cannot be synthesized with these two methods; due to a high cost,
it is difficult to apply the CVD and the chemical exfoliation in
manufacturing of electromobile battery material.
[0006] With respect to application of the lithium battery, the
graphene is regarded as a new-generation cathode material; graphite
is taken as the principal commercial cathode material at present,
and has high stability and high coulombic efficiency, but its
electric capacity is subject to a theoretical capacitance (372
mAh/g, LiC6). To improve the electric capacity thereof, many
researches attempt to produce defects or a functional group on the
surface of the graphite, but achievements are limited; recent
documents also discuss the energy storage feature of the graphene
material, and it is found that a wider graphite interlayer spacing
and a higher single-layer graphite sheet allow more lithium ions to
undergo an intercalation reaction, so as to improve the energy
storage feature of the material. The Honma research team shows that
a capacitance of the cathode of the graphene may reach 540 mAh/g,
and has a certain cycle life. In addition, if C60 and carbon
nanotubes (CNTs) are introduced into a graphene manufacturing
process to form a composite material so as to cause change of a
microstructure, a capacitance of the material can be increased to.
730 mAh/g and 784 mAh/g separately, which further verifies that the
carbon material has a higher electric capacity when having a larger
interlayer spacing. Moreover, the team further uses reactive
stannic oxide (SnO.sub.2) and graphene to form a composite
electrode, a three-dimensional buffering structure can be
generated, and the whole cycle life can be further prolonged.
Although the existing graphene has rather unique features and
accordingly has an application potential, its application in the
lithium battery still brings a defect of a high irreversible
capacitance caused by a high oxygen-contained functional group and
a larger area.
[0007] At present, fabrication of graphene mostly uses a method
disclosed by Hummers in 1957, where graphite is first oxidized into
graphite oxide by using strong acid, where the use of the strong
acid aims to increase the interlayer spacing (0.335 nm or 0.6 to
1.1 nm) of graphene generated later, and further reduce a bond (7
MPa or 2.6 MPa) between layers; the graphite oxide formed by using
the strong acid is composed of multiple graphene oxide sheets, an
oxygen-contained functional group thereof attached after chemical
modification renders the graphite oxide hydrophilic, such a
hydrophilic feature enables water molecules or other intercalating
agents to enter graphene layers, and then graphite intercalation
composites (GICs) are formed; and finally, after a rapid
temperature rise, the GICs are inflated in a c-axis direction by
instantaneous evaporation of the intercalating agents, and then a
graphene oxide thin film is exfoliated. Therefore, intercalants are
added; and are vaporized by rapid heating, and a volume expansion
ratio after the vaporization reaches up to 300 times; and then nano
graphene plates are obtained after reduction and decentralization.
At present, a bottleneck of this manufacturing technology lies in
oxidization, reduction, and decentralization. When the strong acid
is used to oxidize the graphene, hydroxyl and epoxide that are
difficult to be reduced are formed on the surface of the graphene,
which affects electric conductivity of the material; in addition,
because surfaces of graphite oxide and graphite are both
hydrophilic, during reduction, aggregation, that is, a
decentralization difficulty mentioned above, is easily caused by
conversion between hydrophilicity and hydrophobicity of the
material surface; and a large amount of deionized water is needed
to clean the material if the strong acid is used for treatment,
which is not environmentally friendly. In addition, graphite is
incompletely exfoliated; it is reported in a document that a
surface area of the fabricated graphene is about 100 m.sup.2/g to
500 m.sup.2/g and a size thereof is 13*52 nm, and there is a gap
between these values and theoretical values.
[0008] U.S. Pat. No. 7,745,047 B2 discloses a fabrication method of
a cathode material of a lithium battery, where a precursor of
graphite oxide and different cathode materials are mixed and
heated, and graphene is formed after exfoliation/reduction.
However, an ECG manufacturing process requires multiple chemical
steps, and easily causes environmental pollution; and quality of
the graphene is easily affected by a raw material status, an
exfoliation procedure, and a reduction condition, and therefore, it
is difficult to stably control this process. Therefore, when this
method is applied in industrial mass production of ECG-surface
modified cathode and anode materials, product properties cannot be
maintained.
[0009] U.S. Pat. No. 1,447,993 describes a cathode material and a
negative plate, and discloses a cathode material with a self-repair
capability and a negative plate, where an unsaturated-compound
functional group and carbon-contained substrate surface undergo an
addition reaction, to form a chemical bond, for example, a chemical
covalent bond, where this addition reaction mechanism is
reversible. When a partial high-molecular cross-linked structure of
unsaturated compound bonded to the carbon-contained substrate
surface is broken due to an external factor (for example, heat or
stress), because of the reversible mechanism of the addition
reaction, the broken cross-linked structure undergoes an addition
reaction again in a manner of providing high-molecular energy (for
example, heating), so as to recover to an original structure;
therefore, on the carbon-contained substrate surface, a protective
layer formed by the unsaturated compound chemically bonded to the
carbon-contained substrate surface has a self-repair capability. In
addition, the protective layer formed by the unsaturated compound
on the carbon-contained substrate can improve the electrochemical
activity of the carbon surface, perfect compatibility between the
carbon-contained substrate surface and an electrolyte interface,
and further maintain integrality of the original substrate.
[0010] U.S. Pat. No. 1,480,426 describes a graphene manufacturing
method, where the method includes: setting a first electrode and a
second electrode in an electrolyte, where ions in the electrolyte
are used as inserts and the first electrode is a graphite material;
performing a step of intercalation of the graphite material under a
first bias; performing a step of exfoliation of the graphite
material by using the inserts under a second bias; and finally,
taking a solid part from the electrolyte as electrochemical
graphene. An oxygen content in the electrochemical graphene
obtained by using this method is far below that in the graphene
(ECG) obtained by using chemical exfoliation, and therefore,
conductivity of the electrochemical graphene is much higher than
that of the ECG, and the electron conduction velocity is further
enhanced.
[0011] To sum up, in the prior art, the SET film is coated on a
negative plate in an attraction manner, and therefore is easily
separated from the negative plate; and its application in a lithium
battery still brings a defect of a high irreversible capacitance
caused by a high oxygen-contained functional group and a larger
area; moreover, in an oxidization, reduction, and decentralization
reaction, when strong acid is used to oxidize the graphene,
hydroxyl and epoxide that are difficult to be reduced are formed on
the surface of the graphene, which affects conductivity of the
material.
SUMMARY
[0012] An objective of the present invention provides a method for
manufacturing a negative plate of a secondary battery, which
fabricates a coarse surface microstructure on a surface of copper
foil, so as to increase a surface area of the copper foil to
strengthen attachment between graphene and the copper foil; and
then after deposition of graphene, repairs, by using an excimer
laser, a defect structure inside the graphene deposited on the
copper foil. The method can increase a reversible capacitance of a
battery and greatly prolong a cycle life of the whole graphene
cathode.
[0013] The method for manufacturing a negative plate of a secondary
battery according to the present invention comprises the following
steps: providing multiple sheets of functional graphene;
compressing the functional graphene to form a graphene target;
providing copper foil, and forming a microstructure on a surface of
the copper foil, so as to strengthen attachment between a graphene
layer and the copper foil; depositing the graphene target on the
microstructure of the surface of the copper foil, to form the
graphene layer; and repairing the graphene layer by using an
excimer laser,
[0014] As described above, in the method for manufacturing a
negative plate of a secondary battery according to the present
invention, coarse surface is fabricated on a surface of copper foil
by using a femtosecond laser; preferably, a subtler microstructure
is further fabricated by using a picosecond laser, and then, a
graphene target is deposited on the copper foil to form a graphene
layer; and finally, a defect structure of graphene is repaired by
using an excimer laser. In this way, by using the microstructure
fabricated on the coarse surface of the copper foil, attachment
between the graphene and the copper foil can be improved; and
finally the defect structure inside the graphene is repaired by
using the excimer laser, which can increase a reversible
capacitance of a battery and greatly prolong a cycle life of the
whole graphene cathode.
[0015] With the method for manufacturing a negative plate of a
secondary battery according to the present invention, the graphene
layer contains oxygen below 20 wt %, and has penetrability of 90%
or higher and sheet resistance below 10 k.OMEGA./sq, where the
sheet resistance is calculated by taking the film thickness of the
graphene as 1.5 nm to 5 nm.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a flowchart of a method for manufacturing
functional graphene according to the present invention; and
[0017] FIG. 2 is a flowchart of a method for manufacturing a
negative plate of a battery according to the present invention.
DETAILED DESCRIPTION
[0018] To make the foregoing and other objectives, features, and
advantages of the present invention more comprehensible, the
present invention is described in detail below with reference to
the accompanying drawings.
[0019] First, referring to FIG. 1, FIG. 1 is a flowchart of a
method for manufacturing functional graphene according to the
present invention. The method for manufacturing functional graphene
includes: In Step S100, add graphite to potassium nitrate
(NaNO.sub.3) and sulfuric acid (H.sub.2O.sub.4) oxidant, to form a
graphite solution, and stir the graphite solution. Then in Step
S101, add catalyst manganese peroxide (KMnO.sub.4) to the graphite
solution, and stir the solution.
[0020] As described above, the graphite is 2 grams, manganese
peroxide is 3 grams, potassium nitrate is 0.2 to 0.75 grams,
sulfuric acid is 70 milliliters, stirring temperature is below
80.degree. C., and a stirring time is 2 hours.
[0021] Then, in Step S110, add deionized water to the graphite
solution, perform ultrasound oscillation, abandon supernatant fluid
after the oscillated graphite solution stands still and layers, and
then add hydrochloric acid water solution for cleaning, where a
ratio of hydrochloric acid to water in the hydrochloric acid water
solution is 1:10.
[0022] After the deionized water is added to the graphite solution,
Step S1101 is further included, where hydrogen peroxide
(H.sub.2O.sub.2) of 3 grams is added as a catalyst, then deionized
water is used again for attenuation, and afterwards, ultrasound
oscillation is performed, where an ultrasound oscillation time is
30 minutes.
[0023] Then, in Step S120, abandon supernatant fluid after
centrifugation of the graphite solution at a rotation speed, and
repeatedly clean and centrifuge the solution by using the
hydrochloric acid water solution, to obtain a graphite oxide
solution, where the rotation speed is about 4000 rpm and a
centrifugation time is 5 minutes.
[0024] Then, in Step S130, add hydrazine to the graphite oxide
solution, where the graphite oxide solution is 3000 CC; and the
added 50 ml hydrazine is recirculated (recirculate to improve a
reaction effect) for 24 hours at 100.degree. C.
[0025] In Step S140, dry the graphite oxide solution, to obtain
functional graphene, where the drying temperature is 100.degree.
C.
[0026] Then, a method for manufacturing a negative plate of a
battery is performed. Referring to FIG. 2, FIG. 2 is a flowchart of
a method for manufacturing a negative plate of a battery according
to the present invention, First, Step S200 is performed, where
multiple sheets of functional graphene is provided, and the
functional graphene is compressed to form a graphene target (Step
S210).
[0027] Then in step S220, provide copper foil, and form a
microstructure on a surface of the copper foil. In this embodiment,
the microstructure is formed on the surface of the copper foil by
using a femtosecond laser, to coarsen the surface of the copper
foil, where the microstructure is a trench structure or a ladder
structure. Preferably, after the microstructure is formed on the
surface of the copper foil by using the femtosecond laser, the
surface of the copper foil is cut by using a picosecond laser to
perform subtler processing, that is, a subtler microstructure is
formed on the surface of the microstructure by using the picosecond
laser, to increase a surface area of the copper foil, so as to
strengthen attachment between a deposited graphene layer and the
copper foil in a subsequent step.
[0028] Then, in Step S230, deposit the graphene target on the
copper foil to form a graphene layer. In this way, because the
coarse surface microstructure has been fabricated on the surface of
copper foil, attachment between the graphene and the copper foil
can be strengthened. Finally, in Step S240, repair the graphene
layer on the copper foil by using an excimer laser. Because a
lattice in the graphene target status presents a perfect hexagonal
lattice and has better mechanical performance, a lattice of
graphene formed through deposition on the microstructure of the
copper foil later has defects, and presents a loose status.
Therefore, after processing and annealing are performed on the
graphene by using the excimer laser, the lattice thereof returns to
the hexagonal lattice status after repairing, thereby increasing a
reversible capacitance of a battery and greatly prolonging a cycle
life of the whole graphene cathode.
[0029] With the method for manufacturing a negative plate of a
secondary battery according to the present invention, the graphene
layer contains oxygen below 20 wt %, and has penetrability of 90%
or higher and sheet resistance below 10 k.OMEGA./sq, where the
sheet resistance is calculated by considering the graphene layer
formed after a graphene target is deposited on the copper foil,
where the film thickness of the graphene layer is 1.5 nm to 5
nm.
[0030] With the foregoing method in the present invention, a
reversible capacitance of a battery is mainly increased. A charging
capacitance at the first ring is greatly increased to 1333 mAh/g, a
discharging capacitance is also increased to 643 mAh/g, and this
value is 1.5 times greater than that of commercial graphite. For
the cycle life of 100 rings, the capacitance can be increased from
200 mAh/g in the original situation to 450 mAh/g, which greatly
prolongs the cycle life of the whole graphene cathode. Further,
after charging and discharging for 200 rings, the capacitance
hardly attenuates and reaches 648 mAh/g, which is beyond an index
of a button cell and achieves an index of a vehicle battery cathode
material.
[0031] In the present invention, a coarse surface microstructure is
fabricated on a surface of copper foil by using a femtosecond laser
and a picosecond laser, which strengthens attachment between a
graphene layer and the copper foil; then, a graphene target is
deposited on the copper coil to form the graphene layer; and
finally, a defect structure of the graphene layer deposited on the
copper foil is repaired by using an excimer laser, thereby
increasing a reversible capacitance of a battery and greatly
prolonging a cycle life of the whole graphene cathode.
[0032] To sum up, preferred implementation manners or embodiments
of technical solutions adopted by the present invention to solve
the problems are merely descried, and are not intended to limit the
patent implementation scope of the present invention. Any
implementation conforming to the patent implementation scope of the
present invention, or equivalent variations and modifications made
according to the patent scope of the present invention all fall
within the patent scope of the present invention.
* * * * *